Langsee

Langsee or Längsee may refer to:
 * Längsee (Kärnten), a lake of Carinthia, Austria
 * Längsee (Tyrol), a lake of Tyrol, Austria
 * Langsee (Schleswig), a lake in Angeln, Kreis Schleswig-Flensburg, Schleswig-Holstein, Germany
 * Langsee (Mecklenburg), a lake in the Rostock district in Mecklenburg-Vorpommern, Germany